1. Field of the Invention
The present invention relates to an intake structure in a V-type internal combustion engine having cylinders banked in V pattern.
2. Description of Background Art
There is an example of a motorcycle with a front-rear V-type internal combustion engine mounted thereon, wherein a throttle body is interposed in an intake passage extended to the inside of the V banks of the V-type internal combustion engine and bent to be parallel to a crankshaft (for example, see Japanese Patent Laid-open No. 2002-89415).
The throttle body disclosed in Japanese Patent Laid-open No. 2002-89415 is provided with a bypass passage bypassing a throttle valve, and the bypass passage is opened and closed by a bypass valve, according to the structure disclosed.
The bypass valve is driven to open and close by a valve body drive mechanism for driving through expansion and contraction of a wax.
In Japanese Patent Laid-open No. 2002-89415, the direction in which the bypass valve is moved to open and close is the direction in which the intake passage bent to be parallel to a crankshaft is directed, i.e., the direction in which the crankshaft is directed (the width direction of a vehicle body and the V-type internal combustion engine), and a drive shaft of the valve body drive mechanism is disposed coaxially with the moving direction of the bypass valve.
Therefore, the valve body drive mechanism filled with the wax, the drive shaft and the bypass valve are aligned rectilinearly in the width direction of the internal combustion engine, so that the throttle body comprising these elements tends to be large in the width direction.
In Japanese Patent Laid-open No. 2002-89415, the valve body drive mechanism is designed for driving through the expansion and contraction of the wax, so that the throttle body is composed substantially of the valve body drive mechanism itself, and the throttle body may not necessarily be so large in the width direction. When an electric actuator is adopted, the throttle body is more enlarged in the width direction, and an air cleaner disposed on a lateral side of the throttle body is more projected to the lateral side, thereby enlarging the vehicle width and widening the distance between the knees of the rider.